Moisture-curable, polyether urethanes with reactive silane groups and their use as sealants, adhesives and coatings

ABSTRACT

A moisture curable, alkoxysilane-functional polyether urethanes containing  
     a) 20 to 90% by weight, of a polyether urethane containing two or more reactive silane groups and polyether segments having a number average molecular weight (Mn) of at least 3000 and a degree of unsaturation of less than 0.04 milliequivalents/g, where the sum of Mn of the polyether segments averages 6000 to 20,000, and the reactive silane groups are incorporated by reaction of an isocyanate-reactive group with a compound of formula 
     OCN—Y—Si—(X) 3   (I) 
     b) 10 to 80% by weight, of a polyether urethane containing one reactive silane group and one or more polyether segments having Mn of 1000 to 15,000, where the reactive silane groups are incorporated by the reaction of an isocyanate group with a compound of formula

CROSS REFERENCE TO RELATED PATENT APPLICATION

[0001] This application is a Continuation-in-Part of U.S. Ser. No.10/174,039, filed Jun. 18, 2002.

FIELD OF THE INVENTION

[0002] The present invention relates to moisture-curable urethanescontaining reactive silane groups and prepared from polyether polyolshaving a low degree of unsaturation and to the use of thesepolyurethanes as sealants, adhesives and coatings.

BACKGROUND OF THE INVENTION

[0003] Polyether urethanes containing reactive silane groups, alsoreferred to as silane-terminated polyurethanes (STPs), and their use assealants and adhesives is known and described, e.g., in U.S. Pat. Nos.5,554,709; 4,857,623; 5,227,434 and 6,197,912; and WO 02/06367. Thesilane-terminated polyurethanes may be prepared by various methods. Inone method the silane-terminated polyurethanes are prepared by reactingdiisocyanates with polyether polyols to form isocyanate-terminatedprepolymers, which are then reacted with aminosilanes to form thesilane-terminated polyurethanes. The sealants may also be prepared byreacting unsaturated monools with diisocyanates to form intermediatescontaining unsaturated end groups and then converting these unsaturatedgroups to alkoxysilane groups by hydrosilylation. In another method thesealants are prepared in one step by the reaction of polyether diolswith isocyanatosilanes.

[0004] To be useful as sealants the silane-terminated polyurethanesshould have a number average molecular weight of 6000 to 20,000. Onemethod of obtaining this molecular weight is to use polyether diolsprepared by the KOH process and having a molecular weight of 2000 toprepare the isocyanate-terminated prepolymers. The presence of urethanegroups causes the products to have a high viscosity. To achieve suitableapplication viscosities, the high viscosity is reduced by the additionof higher amounts of plasticizer and lesser amounts of fillers,resulting in more expensive sealant products.

[0005] Another method of obtaining high molecular weight sealants is byusing high molecular weight polyether diols having a low degree ofunsaturation and prepared using special catalysts as described in EP-A0,546,310, EP-A 0,372,561 and DE-A 19,908,562. When these polyetherdiols are used, the resulting sealants have excellent tensile strength,but the sealants are too brittle for many applications because theelongation is too low and the 100% modulus is too high.

[0006] It is an object of the present invention to provide polyetherurethanes that have reactive silane groups and are suitable for use assealants, adhesives and coatings which possess high tensile strengthsand elongations and have a reduced 100% modulus when compared withexisting products.

[0007] This object may be achieved with the polyether urethanescontaining reactive silane groups according to the present invention.These polyether urethanes contain a mixture of polyether urethanescontaining two or more reactive silane groups with polyether urethanescontaining one reactive silane group. The polyether urethanes containingtwo or more reactive silane groups are prepared from high molecularweight polyether polyols having a low degree of unsaturation and thereactive silane groups are incorporated by the use of isocyanatosilanes.In the polyether urethanes containing one reactive silane group, thereactive silane groups are incorporated by the use of secondaryamino-functional silanes.

[0008] The silane-terminated polyether urethanes according to theinvention are suitable for the preparation of sealants or adhesives thathave higher tensile strengths and elongations and lower 100% moduli. Dueto the fact that these polyether urethanes have a low viscosity, sealantcompositions can be formulated with less of the more expensiveplasticizers and more of the less expensive fillers, resulting in lessexpensive sealants.

[0009] The preparation of sealants from mixtures of polyfunctional andmonofunctional silane-terminated polyurethanes is known and disclosed inU.S. Pat. Nos. 5,554,709 and 4,857,623 and WO 02/06367. However, thesereferences do not disclose the use of polyether polyols having a lowdegree of unsaturation and aspartate-functional silanes to prepare thesealants.

[0010] The preparation of silane-terminated polyether urethanes fromaspartate-functional silanes is disclosed in U.S. Pat. No. 5,364,955 andWO 98/18843. In both of these references the polyethers used to preparepolyether urethanes do not have a low degree of unsaturation. Inaddition, mixtures of polyfunctional and monofunctionalsilane-terminated polyurethanes are not disclosed. Finally, in thelatter reference the polyethers must contain 15 to 40% by weight ofethylene oxide units.

[0011] WO 00/26271 discloses the preparation of silane-terminatedpolyether urethanes from polyether polyols having a low degree ofunsaturation and aspartate-functional silanes. The products are preparedby reacting diisocyanates with high molecular weight polyether diols toform NCO prepolymers, which are then capped with aspartate-functionalsilanes to form silane-terminated polyether urethanes. This applicationdoes not disclose mixtures of disilane-terminated polyether urethaneswith polyether urethanes containing one reactive silane group.

[0012] U.S. Pat. No. 6,265,517 describes a similar process for preparingsilane-terminated polyether urethanes from polyether polyols having alow degree of unsaturation and aspartate-functional silanes. The patentrequires the starting polyol to have a monool content of less than 31mole %, and teaches that a relatively high monool content is highlyundesirable because monools react with isocyanates thereby reducingcrosslinking and curing of the prepolymer. The patent also requires theaspartate silanes to be prepared from dialkyl maleates in which thealkyl groups each contain more than four carbon atoms.

[0013] EP 0,372,561 discloses polyether urethanes containing reactivesilane groups and prepared from polyether polyols having a low degree ofunsaturation. In addition, polyether urethanes containing one reactivesilane group are disclosed. This application fails to recognize thenecessity of using secondary amino-functional silanes to incorporatereactive silane groups into the polyether urethane containing onereactive silane group.

[0014] Copending applications Ser. Nos. 10/160,463, 10/173,919,10/160,479 and 10/160,364, disclose alkoxysilane-functional polyetherurethanes containing a mixture of polyether urethanes containing two ormore reactive silane groups with polyether urethanes containing onereactive silane group. The polyether urethanes containing two or morereactive silane groups are prepared from high molecular weight polyetherpolyols having a low degree of unsaturation.

SUMMARY OF THE INVENTION

[0015] The present invention relates to moisture curable,alkoxysilane-functional polyether urethanes containing

[0016] a) 20 to 90% by weight, based on the weight of a) and b), of apolyether urethane containing two or more reactive silane groups and oneor more polyether segments, wherein the polyether segments have a numberaverage molecular weight of at least 3000 and a degree of unsaturationof less than 0.04 millie-quivalents/g, provided that the sum of thenumber average molecular weights of all of the polyether segments permolecule averages 6000 to 20,000, and wherein the reactive silane groupsare incorporated by the reaction of an isocyanate-reactive group with acompound corresponding to the formula

ONC—Y—Si—(X)₃  (I)

[0017] wherein

[0018] X represents identical or different organic groups which areinert to isocyanate groups below 100° C., provided that at least two ofthese groups are alkoxy or acyloxy groups and

[0019] Y represents a linear or branched alkylene group containing 1 to8 carbon atoms, and

[0020] b) 10 to 80% by weight, based on the weight of a) and b), of apolyether urethane containing one reactive silane group and one or morepolyether segments having a number average molecular weight of 1000 to15,000, wherein the reactive silane groups are incorporated by thereaction of an isocyanate group with a compound corresponding to theformula

[0021] wherein

[0022] R₁ represents an organic group which is inert to isocyanategroups at a temperature of 100° C. or less.

[0023] The present invention also relates to sealant, adhesive andcoating compositions containing these polyether urethanes.

DETAILED DESCRIPTION OF THE INVENTION

[0024] In the moisture-curable, polyether urethanes according to thepresent invention polyether urethanes a) are present in a minimum amountof 20% by weight, preferably 30% by weight and more preferably 40% byweight. The maximum amount of polymers a) is 90% by weight, preferably80% by weight and more preferably 70% by weight. Polyether urethanes b)are present in a minimum amount of at least 10% by weight, preferably20% by weight and more preferably 30% by weight. The maximum amount ofpolymers b) is 80% by weight, preferably 70% by weight and morepreferably 60% by weight. The preceding percentages are based on thetotal weight of polyether urethanes a) and b).

[0025] Suitable polymers for use as component a) include polyetherurethanes containing one or more, preferably one, polyether segmenthaving a number average molecular weight of 3000 to 20,000, preferably6000 to 15,000 and more preferably 8000 to 12,000. When the polyethersegments have a number average molecular weight of 3000, for example,then two or more of these segments must be present so that the numberaverage molecular weights of all of the polyether segments per moleculeaverages 6000 to 20,000. Polymers a) also contain two or more,preferably two reactive silane groups. The reactive silane groups areincorporated by the reaction of an isocyanate-reactive group with anisocyanatosilane corresponding to formula I.

[0026] In accordance with the present invention the term “reactivesilane group” means a silane group containing at least two alkoxy oracyloxy groups as defined by substituent “X”. A silane group containingtwo or three alkoxy and/or acyloxy groups is considered to be onereactive silane group. Also, a urethane is a compound containing one ormore urethane and/or urea groups. These compounds preferably contain oneor more urethane groups and may optionally contain urea groups. Morepreferably, these compounds contain both urethane and urea groups.

[0027] Polymers a) may be prepared by several methods. For example, theymay be prepared by reacting a high molecular weight polyether containingat least two isocyanate-reactive groups, preferably hydroxyl groups,with an isocyanatosilane corresponding to formula I. to form polymersa). This method is preferred in accordance with the present inventionbecause polymers a) are directly formed with a minimum amount ofconnecting groups, e.g., urethane or urea groups.

[0028] Indirect methods for forming polymers a) are also suitable. Forexample, the isocyanatosilane may be reacted with an equimolar amount ofa compound containing two isocyanate-reactive groups, such as a diol ora diamine, to form a intermediate compound containing oneisocyanate-reactive group. The intermediate compound may then be reactedwith an NCO prepolymer prepared by reacting an excess of apolyisocyanate, preferably a diisocyanate, with the previously describedhigh molecular weight polyether. These NCO prepolymers are described incopending application, Attorney's Docket No. MD-01-66-LS, hereinincorporated by reference. The indirect methods are less preferred sincethey introduce a greater number of connecting groups, which cansubstantially increase the viscosity of polyether urethanes a).

[0029] Suitable isocyanatosilanes are those corresponding to formula I

ONC—Y—Si—(X)₃  (I)

[0030] wherein

[0031] represents identical or different organic groups which are inertto isocyanate groups below 100° C., provided that at least two of thesegroups are alkoxy or acyloxy groups, preferably alkyl or alkoxy groupshaving 1 to 4 carbon atoms and more preferably alkoxy groups and

[0032] Y represents a linear or branched alkylene group containing 1 to8 carbon atoms, preferably a linear group containing 2 to 4 carbon atomsor a branched group containing 5 to 6 carbon atoms, more preferably alinear group containing 3 carbon atoms.

[0033] Especially preferred are compounds in which X represents methoxy,ethoxy groups or propoxy groups, more preferably methoxy or ethoxygroups, and Y is a linear group containing 3 carbon atoms. Examples ofsuitable isocyanatosilanes include3-isocyanatopropyl-methyldimethoxysilane,3-isocyanatopropyl--trimethoxysilane and3-isocyanatopropyl-triethoxysilane. 3-isocyanatopropyl-trimethoxysilane(Silquest Y-5187, available from OSI Corporation) is especiallypreferred.

[0034] Suitable polyols for preparing polymers a) are polyether polyols,preferably diols, having a number average molecular weight of at least3000, in some cases at least 6000 and in other cases at least 8000.Also, the number average molecular weight of the polyether polyol can beup to 20,000, in some cases up to 15,000 and in other cases up to12,000. The number average molecular weight of the polyether polyol canvary and range between any of the values recited above.

[0035] The polyethers have a maximum total degree of unsaturation of 0.1milliequivalents/g (meq/g) or less, in some cases less than 0.04 (meq/g)in other cases less than 0.02 meq/g, in some situations less than 0.01meq/g, in other situations 0.007 meq/g or less, and in particularsituations 0.005 meq/g or less. The amount of unsaturation will varydepending on the method used to prepare the polyether as well as themolecular weight of the polyether. Such polyether diols are known andcan be produced by, as a non-limiting example, the propoxylation ofsuitable starter molecules. As another non-limiting example, minoramounts (up to 20% by weight, based on the weight of the polyol) ofethylene oxide can be used. If ethylene oxide is used, it is preferablyused as the initiator for or to cap the polypropylene oxide groups.Non-limiting examples of suitable starter molecules include diols suchas ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol,1,6 hexanediol and 2-ethylhexanediol-1,3. Also suitable are polyethyleneglycols and polypropylene glycols.

[0036] Suitable methods for preparing polyether polyols are known andare described, for example, in EP-A 283 148, U.S. Pat. No. 3,278,457,U.S. Pat. No. 3,427,256, U.S. Pat. No. 3,829,505, U.S. Pat. No.4,472,560. U.S. Pat. No. 3,278,458, U.S. Pat. No. 3,427,334, U.S. Pat.No. 3,941,849, U.S. Pat. No. 4,721,818, U.S. Pat. No. 3,278,459, U.S.Pat. No. 3,427,335 and U.S. Pat. No. 4,355,188. They are preferablyprepared using double metal cyanides as catalysts.

[0037] In addition to the polyether polyols, minor amounts (up to 20% byweight, based on the weight of the polyol) of low molecular weightdihydric and trihydric alcohols having a molecular weight 32 to 500 canalso be used. Suitable examples include ethylene glycol, 1,3-butandiol,1,4-butandiol, 1,6-hexandiol, glycerine or trimethylolpropane. However,the use of low molecular weight alcohols is less preferred.

[0038] It is also possible in accordance with the present invention touse aminopolyethers instead of the polyether polyols. Theaminopolyethers may be prepared by aminating the corresponding polyetherpolyols in known manner.

[0039] Similarly to polymers a), polymers b) also contain one or morepolyether segments, but they only contain one reactive silane group.Polymers b) may be prepared by several methods. For example, they may beprepared by reacting a high molecular weight polyether containing oneisocyanate-reactive group, preferably a hydroxyl group, with an excessof a polyisocyanate, preferably a diisocyanate. The amount of theisocyanate and polyether is chosen such that the resulting productcontains one isocyanate group.

[0040] For example, when reacting a diisocyanate with a monool usingequimolar mixtures of the reactants, the resulting product contains anaverage of one isocyanate group. In addition to the monoisocyanateintermediate, which is the 1/1 adduct of the monool and diisocyanate,the reaction mixture also contains minor amounts of non-functionalpolymers c), which are formed by the reaction of two molecules of themonool with one molecule of the diisocyanate. The reaction mixture mayalso contain a minor amount of unreacted diisocyanate, which can beremoved, e.g., by distillation, or which can remain in the reactionmixture.

[0041] In accordance with the present invention it is also possible toreact additional quantities of the monool with the diisocyanate. Whenthe reaction is carried out in this manner, additional amounts ofnon-functional polymers c) are formed. These polymers remain in thereaction mixture and function as plasticizers during the subsequent useof the moisture-curable, polyether urethanes according to the invention.

[0042] The reaction mixture containing the monoisocyanate intermediateis reacted with a compound containing an isocyanate-reactive group,preferably an —NH group, and one or more, preferably one reactive silanegroup to form polyether urethane b). The reaction mixture also containspolymers d), which are the reaction products of any monomericdiisocyanates present in the reaction mixture with theisocyanate-reactive silanes. Polymers d) are considered a part ofpolyether urethane b), even though they contain two reactive silanegroups.

[0043] Non-functional polymers c) are preferably present in an amount ofless than 60% by weight, more preferably less than 30% by weight andmost preferably less than 10% by weight, based on the weight ofpolyether urethane b). When polymers c) are present, they are preferablypresent in an amount of at least 0.1% by weight, more preferably atleast 0.5% by weight.

[0044] Polymers d) are preferably present in an amount of less then 2%by weight, more preferably less than 1% by weight, based on the weightof polyether urethane b). When polymers d) are present, they arepreferably present in an amount of at least 0.1% by weight and morepreferably at least 0.5% by weight, based on the weight of polyetherurethane a).

[0045] Polymers b) may also be prepared by reversing these steps andreacting an excess of a polyisocyanate with an isocyanate-reactivesilane and then reacting the resulting intermediate with the highmolecular weight polyether. Mixtures of polymers b), c) and e) will alsobe formed when the process steps are carried out in this order.

[0046] Suitable polyisocyanates which may be used to prepare polymers b)are known and include monomeric organic diisocyanates represented by theformula, R(NCO)₂, in which R represents an organic group obtained byremoving the isocyanate groups from an organic diisocyanate having amolecular weight of 112 to 1,000, preferably 140 to 400. Preferreddiisocyanates are those represented by the above formula in which Rrepresents a divalent aliphatic hydrocarbon group having from 4 to 18carbon atoms, a divalent cycloaliphatic hydrocarbon group having from 5to 15 carbon atoms, a divalent araliphatic hydrocarbon group having from7 to 15 carbon atoms or a divalent aromatic hydrocarbon group having 6to 15 carbon atoms.

[0047] Examples of suitable organic diisocyanates include1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate,2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 1,1 2-dodecamethylenediisocyanate, cyclohexane-1,3- and -1,4-diisocyanate,1-isocyanato-2-isocyanatomethyl cyclopentane, 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl-cyclohexane (isophoronediisocyanate or IPDI), bis-(4-isocyanato-cyclohexyl)-methane, 1,3- and1,4-bis-(isocyanatomethyl)-cyclohexane,bis-(4-isocyanatocyclo-hexyl)-methane, 2,4′-diisocyanato-dicyclohexylmethane, bis-(4-isocyanato-3-methyl-cyclohexyl)-methane,α,α,α′,α′-tetramethyl-1,3- and/or -1,4-xylylene diisocyanate, 1-isocyanato-1-methyl-4(3)-isocyanatomethyl cyclohexane, 2,4- and/or2,6-hexahydro-toluylene diisocyanate, 1,3- and/or 1,4-phenylenediisocyanate, 2,4-and/or 2,6-toluylene diisocyanate, 2,4- and/or4,4′-diphenylmethane diisocyanate and 1,5-diisocyanato naphthalene andmixtures thereof.

[0048] Monomeric polyisocyanates containing 3 or more isocyanate groupssuch as 4-isocyanatomethyl-1,8-octamethylene diisocyanate and aromaticpolyisocyanates such as 4,4′,4″-triphenylmethane triisocyanate andpolyphenyl polymethylene polyisocyanates obtained by phosgenatinganiline/formaldehyde condensates may also be used. Also suitable,although less preferred, are polyisocyanate adducts prepared from thepreceding monomeric polyisocyanates and containing isocyanurate,uretdione, biuret, urethane, allophanate, iminooxadiazine dione,carbodiimide and/or oxadiazinetrione groups.

[0049] Preferred diisocyanates includebis-(4-isocyanatocyclohexyl)-methane, 1,6-hexamethylene diisocyanate,isophorone diisocyanate, α,α,α′,α′-tetramethyl-1,3- and/or -1,4-xylylenediisocyanate, 2,4- and/or 2,6-toluylene diisocyanate, and 2,4- and/or4,4′-diphenylmethane diisocyanate. Especially preferred are isophoronediisocyanate, 2,4-toluylene diisocyanate and mixtures of 2,4- and2,6-toluylene diisocyanate.

[0050] Also suitable for preparing polymers b) are the difunctional NCOprepolymers previously set forth for preparing polymers a) by theindirect process. If the NCO prepolymer contains high molecular weightpolyether segments, then low molecular monools can also be used toprepare the previously described monoisocyanate intermediates.

[0051] Suitable monools for preparing polymers b) are polyether monoolshaving a number average molecular weight of 1000 to 15,000, preferably3000 to 12,000 and more preferably 6000 to 12,000. The polyether monoolsare prepared by the alkoxylation of monofunctional starting compoundswith alkylene oxides, preferably ethylene oxide, propylene oxide orbutylene oxide, more preferably propylene oxide. If ethylene oxide isused, it is used in an amount of up to 40% by weight, based on theweight of the polyether. The polyethers are preferably prepared eitherby the KOH process or by mixed metal cyanide catalysis. The latterprocess results in products with low a degree of unsaturation.

[0052] Preferably, the polyethers have a maximum total degree ofunsaturation of 0.1 milliequivalents/g (meq/g) or less, in some casesless than 0.04 (meq/g) in other cases less than 0.02 meq/g, in somesituations less than 0.01 meq/g, in other situations 0.007 meq/g orless, and in particular situations 0.005 meq/g or less. The amount ofunsaturation will vary depending on the method used to prepare thepolyether as well as the molecular weight of the polyether. Thesepolyether monools are known and can be produced by the methods set forthpreviously for preparing the polyether polyols, as a non-!imitingexample by the propoxylation of suitable starter molecules. In anothernon-limiting example, minor amounts (up to 20% by weight, based on theweight of the polyol) of ethylene oxide can also be used. As with thepolyethers a-i), if ethylene oxide is used, it can be used as theinitiator for or to cap the polypropylene oxide groups.

[0053] Examples of suitable starter molecules include aliphatic,cycloaliphatic and araliphatic alcohols, phenol and substituted phenols,such as methanol, ethanol, the isomeric propanols, butanols, pentanolsand hexanols, cyclohexanol and higher molecular weight compounds such asnonylphenol, 2-ethylhexanol and a mixture of C₁₂ to C₁₅, linear, primaryalcohols (Neodol 25, available from Shell). Also suitable areunsaturated alcohols such as allyl alcohol; and hydroxy functionalesters such as hydroxyethyl acetate and hydroxyethyl acrylate. Preferredare the higher molecular weight monohydroxy compounds, especially nonylphenol and mixtures of C₁₂ to C₁₅, linear, primary alcohols.

[0054] It is also possible in accordance with the present invention touse monoaminopolyethers instead of the polyether monools. Theseaminopolyethers may be prepared by aminating the corresponding polyethermonools in known manner.

[0055] Suitable isocyanate-reactive silanes for use in preparingpolymers b) include those corresponding to the formula

[0056] wherein

[0057] X and Y are as previously defined and

[0058] R₁ represents an organic group which is inert to isocyanategroups at a temperature of 100° C. or less, preferably an alkyl,cycloalkyl or aromatic group having 1 to 12 carbon atoms and morepreferably an alkyl, cycloalkyl or aromatic group having 1 to 8 carbonatoms.

[0059] Examples of suitable aminoalkyl alkoxysilanes and aminoalkylacyloxysilanes of formula IV, which contain secondary amino groups,include N-phenylaminopropyl-trimethoxysilane (available as A-9669 fromOSI Corporation), N-cyclohexylaminopropyl-triethoxysilane,N-methyl-aminopropyl-trimethoxysilane,N-butylaminopropyl-trimethoxysilane,N-butylaminopropyl-triacyloxysilane,3-(N-ethyl)amino-2-methylpropyl-trimethoxysilane,4-(N-ethyl)amino-3,3-dimethylbutyl-trimethoxysilane and thecorresponding alkyl diethoxy, alkyl dimethoxy and alkyldiacyloxy-silanes, such as3-(N-ethyl)amino-2-methylpropyl-methyldimethoxysilane.

[0060] A special group of compounds containing alkoxysilane groups andcorresponding to formula II are those containing aspartate groups andcorresponding to formula III

[0061] wherein

[0062] X and Y are as previously defined,

[0063] R₂ and R₅ are identical or different and represent organic groupswhich are inert to isocyanate groups at a temperature of 100° C. orless, preferably alkyl groups having 1 to 9 carbon atoms, morepreferably alkyl groups having 1 to 4 carbon atoms, such as methyl,ethyl or butyl groups and

[0064] R₃ and R₄ are identical or different and represent hydrogen ororganic groups which are inert towards isocyanate groups at atemperature of 100° C. or less, preferably hydrogen.

[0065] The compounds of formula III are prepared by reactingaminosilanes corresponding to formula IV

H₂N—Y—Si—(X)₃  (IV)

[0066] with maleic or fumaric acid esters corresponding to formula V

R₅OOC—CR₃═CR₄—COOR₂  (V)

[0067] Examples of suitable aminoalkyl alkoxysilanes and aminoalkylacyloxysilanes corresponding to formula IV include3-aminopropyl-triacyloxysilane, 3-aminopropyl-methyldimethoxysilane;6-aminohexyl-tributoxysilane; 3-aminopropyl-trimethoxysilane;3-aminopropyl-triethoxysilane; 3-aminopropyl-methyldiethoxysilane;5-aminopentyl-trimethoxysilane; 5-aminopentyl-triethoxysilane;4-amino-3,3-dimethylbutyl-trimethoxysilane and3-aminopropyl-triisopropoxysilane. 3-aminopropyl-trimethoxysilane and3-aminopropyl-triethoxysilane are particularly preferred.

[0068] Examples of optionally substituted maleic or fumaric acid esterssuitable for preparing the aspartate silanes include the dimethyl,diethyl, dibutyl (e.g., di-n-butyl), diamyl, di-2-ethylhexyl esters andmixed esters based on mixture of these and/or other alkyl groups ofmaleic acid and fumaric acid; and the corresponding maleic and fumaricacid esters substituted by methyl in the 2- and/or 3-position. Thedimethyl, diethyl and dibutyl esters of maleic acid are preferred, whilethe diethyl esters are especially preferred.

[0069] The reaction of primary amines with maleic or fumaric acid estersto form the aspartate silanes of formula III is known and described,e.g., in U.S. Pat. No. 5,364,955, which is herein incorporated byreference.

[0070] Instead of using an aminosilane, it is also possible to preparepolyether urethanes b) by using the hydroxy compound obtained byreacting a secondary aminosilane with a cyclic carbonate such asethylene or propylene carbonate.

[0071] In accordance with another embodiment of the present invention itis possible to avoid the need for separately preparing a high molecularweight polyether monool by converting a high molecular weight polyetherdiol into a monool by reacting it with a monioisocyanate. A furtheralternative for preparing a polyether monool is to react one mole of adiol with a monoacid chloride. Another method for preparing a highmolecular weight monool is to react one mole of a monool and one mole ofa diol with one mole of a diisocyanate. Either or both of the monool anddiol may contain high molecular weight polyether segments. The polyethermonools obtained from these processes can then be used to preparepolymers b) using the previously described processes.

[0072] If two moles of a diisocyanate are used in the last process, thenthe resulting product is a monoisocyanate that can be reacted with anisocyanate-reactive compound containing an alkoxysilane group to formpolymers b). Another method for forming this monoisocyanate is to reactan NCO prepolymer, such as those previously described for preparingpolymers a), with a monoalcohol.

[0073] The polyether monoamines, which have also been described assuitable for preparing polymers b), can be reacted in the same manner asthe polyether monools.

[0074] In another embodiment a polyether monool is prepared by thealkoxylation of a hydroxyalkyl (meth)acrylate. The resulting polyethermonool is reacted with a monoisocyanate to form an unsaturatedintermediate. This intermediate is then reacted with a primary orsecondary aminosilane or a thiosilane to incorporate silane groups by aMichael addition.

[0075] The compositions of the present invention may be cured in thepresence of water or moisture to prepare coatings, adhesives orsealants. The compositions cure by “silane polycondensation” from thehydrolysis of alkoxysilane groups to form Si—OH groups and theirsubsequent reaction with either Si—OH or Si—OR groups to form siloxanegroups (Si—O—Si).

[0076] Suitable acidic or basis catalysts may be used to promote thecuring reaction. Examples include acids such as paratoluene sulfonicacid; metallic salts such as dibutyl tin dilaurate; tertiary amines suchas triethylamine or triethylene diamine; and mixtures of thesecatalysts. The previously disclosed, low molecular weight, basicaminoalkyl trialkoxy-silanes, also accelerate hardening of the compoundsaccording to the invention.

[0077] The one-component compositions generally may be eithersolvent-free or contain up to 70%, preferably up to 60% organicsolvents, based on the weight of the one-component composition,depending upon the particular application. Suitable organic solventsinclude those which are known from either from polyurethane chemistry orfrom coatings chemistry.

[0078] The compositions may also contain known additives, such asleveling agents, wetting agents, flow control agents, antiskinningagents, antifoaming agents, fillers (such as chalk, lime, flour,precipated and/or pyrogenic silica, aluminum silicates and high-boilingwaxes), viscosity regulators, plasticizers, pigments, dyes, UV absorbersand stabilizers against thermal and oxidative degradation.

[0079] The one-component compositions may be used with any desiredsubstrates, such as wood, plastics, leather, paper, textiles, glass,ceramics, plaster, masonry, metals and concrete. They may be applied bystandard methods, such as spraying, spreading, flooding, casting,dipping, rolling and extrusion.

[0080] The one-component compositions may be cured at ambienttemperature or at elevated temperatures. Preferably, themoisture-curable compositions are cured at ambient temperatures.

[0081] The invention is further illustrated but is not intended to belimited by the following examples in which all parts and percentages areby weight unless otherwise specified.

EXAMPLES

[0082] The following starting components were used in the examples:

[0083] Preparation of Silane Functional Aspartate (SFA 1)

[0084] An aspartate resin was prepared according to U.S. Pat. No.4,364,955. To a 5 liter flask fitted with agitator, thermocouple,nitrogen inlet and addition funnel with condenser were added 1483 g(8.27 equivalents) of 3-aminopropyl-trimethoxysilane (Silquest A-1110,available from OSI Corporation). The addition funnel was used to admit1423.2 g (8.27 equivalents) of diethyl maleate over a two hour period.The temperature of the reactor was maintained at 25° C. during theaddition. The reactor was maintained at 25° C. for an additional fivehours at which time the product was poured into glass containers andsealed under a blanket of nitrogen. After one week the unsaturationnumber was 0.6 indicating the reaction was ˜99% complete.

[0085] Y-5187

[0086] 3-isocyanatopropyl-trimethoxysilane (Silquest Y-5187, availablefrom OSI Corporation)

[0087] A-1110

[0088] 3-aminopropyl-trimethoxysilane (Silquest A-1110, available fromOSI Corporation)

[0089] Hydroxy polyether 1

[0090] A polyoxypropylene diol (Acclaim 12200, unsaturation=0.007 meq/g,available from Bayer Corporation) having a functionality of 2 and theequivalent weight set forth in Table 1.

[0091] Preparation of hydroxy polyether 2

[0092] Nonylphenol (183 g, 0.89 eq) was charged to a stainless-steelreactor. Zinc hexacyanocobaltate-tert-butyl alcohol complex (0.143 g,prepared as described in U.S. Pat. No. 5,482,908) was added and themixture was heated with stirring under vacuum at 130° C. for one hour toremove traces of water from the nonylphenol starter. Propylene oxide(5517 g, 125.4 eq) was introduced into the reactor over 6 hours. Afterthe epoxide addition was completed, the mixture was heated to 130° C.until no further pressure decrease occurred. The product was vacuumstripped and then drained from the reactor. The resulting polyether hadan OH number of 8.7, an equivalent weight of 6411, unsaturation =0.007meq/g, and a functionality of 1.

[0093] Preparation of hydroxy polyether 3

[0094] Hydroxy polyether 3 was prepared in the same manner as hydroxypolyether 2 except that 175 g (0.80 eq) of nonylphenol and 5625 g (127.8eq) of propylene oxide were used. The resulting polyether had an OHnumber of 7.7, an equivalent weight of 7295, unsaturation=0.009 meq/g,and a functionality of 1.

[0095] Preparation of Silane Terminated Polyurethanes (STP) 1-2 fromisocyanatosilanes

[0096] A 1 liter round bottom flask was fitted with agitator, nitrogeninlet, condenser, heater and addition funnel. Into the flask werecharged the weight of hydroxy polyether and the weight of3-isocyanatopropyl-trimethoxysilane (Silquest Y-5187, available from OSICorporation) listed in Table 1 and 0.05 g dibutyltin dilaurate. Thereaction was heated to 50° C. for 4 hours until no NCO remained asdetermined by an IR spectrum. 1.24 g of vinyl trimethoxysilane was addedas a moisture scavenger.

[0097] Preparation of Silane Terminated Polyurethanes (STP) 3-4 fromaminosilanes

[0098] A 5 liter round bottom flask was fitted with agitator, nitrogeninlet, condenser, heater and addition funnel. Into the flask werecharged the weight of isophorone diisocyanate (IPDI) and the weight ofthe hydroxy polyether listed in Table 1 and 0.8 g dibutyltin dilaurate.The reaction was heated to 60° C. for 3 hours until the theoreticalisocyanate content was reached. The weight of the appropriateaminosilane listed in Table 1 was added. The flask was heated at 60° C.for an additional 1 hour until no NCO remained as determined by an IRspectrum. 19.9 g of vinyl trimethoxy-silane as added as moisturescavenger. TABLE 1 STP # 1 2 3 4 Hydroxy Polyether 1 2 3 2 diol monoolmonool monool Equivalent weight 5817 6411 7295 6411 Charge weight, g238.5 239.9 3682.8 330.5 Equivalents 0.041 0.033 0.500 0.045 IPDI Chargeweight, g — — 112.0 10.0 Equivalents — — 1.010 0.090 Silane type Y-5187Y-5187 SFA 1 A-1110 Charge weight, g 11.1 8.9 185.0 8.3 Equivalents0.041 0.033 0.500 0.045 Resin Viscosity, 4,950 2,800 10,400 15,100 mPa.s@ 25 C. Functionality 2 1 1 1

[0099] Formulation of Silane Sealants

[0100] The STP's were formulated into sealants using the followingtypical formulation and procedure. The difunctional STP's wereformulated alone and in combination with the monofunctional STP's todemonstrate the effects of these combinations.

[0101] Procedure

[0102] The following is the standard sealant/adhesive formulation andprocedure used to formulate all diol and diol/monool blends. Valuesgiven for each formula component are percent by weight of the totalformula weight. A high-speed centrifugal mixer was used to mix theformulation components in the steps given below. Each mixing period wasone minute in length at a speed of 2200 rpm.

[0103] Step 1:

[0104] To a clean dry mixing container were charged the following: STP(blend) 37.5 Plasticizer 17.5 Adhesion Promoter 0.8 Catalyst 0.1Desiccant 0.5

[0105] The ingredients were mixed for one minute in length at a speed of2200 rpm.

[0106] Step 2:

[0107] A portion of the filler was added to the mixing container.

Filler 23.6

[0108] The ingredients were mixed for one minute at a speed of 2200 rpm.

[0109] Step 3:

[0110] The remaining filler was added to the mixing container.

Filler 20.0

[0111] The ingredients were mixed for one minute in length at a speed of2200 rpm.

[0112] Step 4:

[0113] The side of the mix container was scraped and the ingredientswere mixed for one additional minute at a speed of 2200 rpm toincorporate all of the filler into the mixture.

[0114] Step 5:

[0115] The resulting product was degassed at 50° C. and under fullvacuum (>28 mm Hg) for one hour. The material was used immediately.

[0116] Exxon Jayflex DIDP was used as the plasticizer. An aminosilane(Silquest A-1120, available from OSI Corporation) was used as theadhesion promoter. A vinyltrimethoxysilane (Silquest A-171, availablefrom OSI Corporation) was used as the desiccant. The filler used wasSpecialty Minerals Ultra P Flex precipitated calcium carbonate (meanparticle size of 0.07 microns). The catalyst used was dibutyltindilaurate.

[0117] The weight ratios of the diols to monools in the STP portion ofthe sealant formulations were varied as set forth in the followingtable. The weight ratios are based on the total weight of the STP's inthe formulation.

[0118] Cure and Testing of Silane Sealants

[0119] The sealant formulations were cast onto 0.25 inch thickpolyethylene sheets and cured at standard conditions of 20° C., 50%relative humidity for at least two weeks before testing. Tensilestrength, percent elongation and 100% modulus were determined accordingto ASTM D-412. Die “C” tear strengths were determined according to ASTMD-624. The results are set forth in the following table. TABLE 2 SealantProperties Ultimate Modulus Disilane/ Die-C Tensile @ 100% DisilaneMonosilane Monosilane Tear Strength Elongation Elongation Ex. No. STPSTP Ratio (lbs/in) (psi) (psi) (%)  1 (Comp) 1 — — 32 292 188 191  2(Comp) 1 2 80:20 28 254 203 158  3 (Comp) 1 2 60:40 25 201 179 141  4(Comp) 1 2 40:60 13 140 187 95  5 1 3 80:20 28 262 144 239  6 1 3 60:4023 216 122 217  7 1 3 40:60 21 169 78 262  8 (Comp) 1 4 80:20 24 246 164178  9 (Comp) 1 4 60:40 19 211 135 180 10 (Comp) 1 4 40:60 13 157 105171

[0120] The properties set forth in the table demonstrate the advantagesobtained for sealants 5-7 according to the invention. These sealants,which contained monofunctional STP's prepared from a secondaryaminosilane, provide improved ultimate tensile strengths, much lowermoduli at 100% elongation and much higher elongations than comparisonsealants 2-4 and 8-10. The comparison sealants contain monofunctionalSTP's 2 and 4, which were prepared from an isocyanatosilane and aprimary aminosilane, respectively.

[0121] Although the invention had been described in detail in theforegoing for the purpose of illustration, it was to be understood thatsuch detail was solely for that purpose and that variations can be madetherein by those skilled in the art without departing from the spiritand scope of the invention except as it may be limited by the claims.

What is claimed is:
 1. A moisture-curable, alkoxysilane-functionalpolyether urethane comprising a) 20 to 90% by weight, based on theweight of a) and b), of a polyether urethane containing two or morereactive silane groups and one or more polyether segments, wherein thepolyether segments have a number average molecular weight of at least3000 and a degree of unsaturation of less than 0.04 millie-quivalents/g,provided that the sum of the number average molecular weights of all ofthe polyether segments per molecule averages 6000 to 20,000, and whereinthe reactive silane groups are incorporated by the reaction of anisocyanate-reactive group with a compound corresponding to the formulaOCN—Y—Si—(X)₃  (I) wherein X represents identical or different organicgroups which are inert to isocyanate groups below 100° C., provided thatat least two of these groups are alkoxy or acyloxy groups and Yrepresents a linear or branched alkylene group containing 1 to 8 carbonatoms, and b) 10 to 80% by weight, based on the weight of a) and b), ofa polyether urethane containing one reactive silane group and one ormore polyether segments having a number average molecular weight of 1000to 15,000, wherein the reactive silane groups are incorporated by thereaction of an isocyanate group with a

compound corresponding to the formula wherein R₁ represents an organicgroup which is inert to isocyanate groups at a temperature of 100° C. orless.
 2. The polyether urethane of claim 1 wherein X representsidentical or different alkoxy groups having 1 to 4 carbon atoms, Yrepresents a linear radical containing 2 to 4 carbon atoms or a branchedradical containing 5 to 6 carbon atoms and R₁ represents an alkyl,cycloalkyl or aromatic group having 1 to 12 carbon atoms.
 3. Thepolyether urethane of claim 1 wherein the reactive silane groups ofcomponent b) are incorporated as the reaction product of an isocyanategroup and a compound corresponding to the formula

wherein R₂ and R₅ are identical or different and represent organicgroups which are inert to isocyanate groups at a temperature of 100° C.or less and R₃ and R₄ are identical or different and represent hydrogenor organic groups which are inert towards isocyanate groups at atemperature of 100° C. or less.
 4. The polyether urethane of claim 1wherein the reactive silane groups of component b) are incorporated asthe reaction product of an isocyanate group and a compound correspondingto the formula

wherein X represents identical or different alkyl or alkoxy groupshaving 1 to 4 carbon atoms, Y represents a linear radical containing 2to 4 carbon atoms or a branched radical containing 5 to 6 carbon atoms,R₂ and R₅ are identical or different and represent alkyl groups having 1to 4 carbon atoms and R₃ and R₄ represent hydrogen.
 5. The polyetherurethane of claim 1 wherein polyether urethane a) is present in anamount of 30 to 80% by weight and polyether urethane b) is present in anamount of 20 to 70% by weight, wherein the percentages are based on theweight of a) and b).
 6. The polyether urethane of claim 2 whereinpolyether urethane a) is present in an amount of 30 to 80% by weight andpolyether urethane b) is present in an amount of 20 to 70% by weight,wherein the percentages are based on the weight of a) and b).
 7. Thepolyether urethane of claim 3 wherein polyether urethane a) is presentin an amount of 30 to 80% by weight and polyether urethane b) is presentin an amount of 20 to 70% by weight, wherein the percentages are basedon the weight of a) and b).
 8. The polyether urethane of claim 4 whereinpolyether urethane a) is present in an amount of 30 to 80% by weight andpolyether urethane b) is present in an amount of 20 to 70% by weight,wherein the percentages are based on the weight of a) and b).
 9. Thepolyether urethane of claim 1 wherein the polyether segments ofpolyether urethane a) have a number average molecular weight of at least6000 and the polyether segments of component b) have a number averagemolecular weight of 3000 to 12,000.
 10. The polyether urethane of claim2 wherein the polyether segments of polyether urethane a) have a numberaverage molecular weight of at least 6000 and the polyether segments ofcomponent b) have a number average molecular weight of 3000 to 12,000.11. The polyether urethane of claim 3 wherein the polyether segments ofpolyether urethane a) have a number average molecular weight of at least6000 and the polyether segments of component b) have a number averagemolecular weight of 3000 to 12,000.
 12. The polyether urethane of claim4 wherein the polyether segments of polyether urethane a) have a numberaverage molecular weight of at least 6000 and the polyether segments ofcomponent b) have a number average molecular weight of 3000 to 12,000.13. The polyether urethane of claim 5 wherein the polyether segments ofpolyether urethane a) have a number average molecular weight of at least6000 and the polyether segments of component b) have a number averagemolecular weight of 3000 to 12,000.
 14. The polyether urethane of claim6 wherein the polyether segments of polyether urethane a) have a numberaverage molecular weight of at least 6000 and the polyether segments ofcomponent b) have a number average molecular weight of 3000 to 12,000.15. The polyether urethane of claim 7 wherein the polyether segments ofpolyether urethane a) have a number average molecular weight of at least6000 and the polyether segments of component b) have a number averagemolecular weight of 3000 to 12,000.
 16. The polyether urethane of claim8 wherein the polyether segments of polyether urethane a) have a numberaverage molecular weight of at least 6000 and the polyether segments ofcomponent b) have a number average molecular weight of 3000 to 12,000.17. A sealant, adhesive or coating composition containing themoisture-curable, alkoxysilane-functional polyether urethane of claim 1.